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Per Ahlberg - One of the best experts on this subject based on the ideXlab platform.
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The Furongian (upper Cambrian) Alum Shale of Scandinavia: revision of zonation
Lethaia, 2020Co-Authors: Arne Thorshøj Nielsen, Magne Høyberget, Per AhlbergAbstract:The zonation of the Furongian Alum Shale in Scandinavia, based on olenid trilobites, is reviewed and revised. The current scheme is rooted in a detailed zonation introduced in the late 1950s with subzones that subsequently have been elevated to zonal rank. Ten of these zones are difficult to recognize in all Alum Shale districts, and a revised zonation is proposed, focused on unambiguous identification throughout Scandinavia. The difficulties in recognizing zones in some districts mostly relate to biofacies differentiation. Representatives of Ctenopyge are, for instance, common in palaeo-offshore areas, whereas pelturines are rare in these settings and vice versa in palaeo-inboard settings. The following modifications of the olenid zonation are proposed: the Olenus scanicus Zone is renamed the O. scanicus–O. rotundatus Zone; the Ctenopyge similis and Ctenopyge spectabilis zones are replaced by the Sphaerophthalmus modestus–Sphaerophthalmus angustus Zone; the Ctenopyge tumida Zone is renamed the Peltura acutidens–Ctenopyge tumida Zone; the Peltura scarabaeoides Subzone is restored (as a zone) and replaces the Ctenopyge bisulcata and Ctenopyge linnarssoni zones. The Parabolina heres megalops (Sub)Zone is reinstated and replaces the Peltura paradoxa Zone; the Acerocarina granulata and P. costata zones are combined as the Acerocarina granulata–Peltura costata Zone. In addition, the name Proceratopyge nathorsti–Simulolenus alpha Zone is suggested for the polymerid zone corresponding to the upper Miaolingian Agnostus pisiformis Zone. The proposed changes reduce the number of Furongian Zones to 23, allocated to six superzones. No subzones are recognized, but some zones can potentially be subdivided for improved local correlation. The stratigraphical ranges of all Furongian olenid trilobites and agnostoids described from Scandinavia are summarized. (Less)
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Integrated Cambrian biostratigraphy and carbon isotope chemostratigraphy of the Grönhögen-2015 drill core, Öland, Sweden
Geological Magazine, 2019Co-Authors: Per Ahlberg, Frans Lundberg, Mikael Erlström, Mikael Calner, Anders Lindskog, Peter Dahlqvist, Michael M. JoachimskiAbstract:The Gronhogen-2015 core drilling on southern Oland, Sweden, penetrated 50.15 m of Cambrian Series 3, Furongian and Lower–Middle Ordovician strata. The Cambrian succession includes the Aleklinta Member (upper Stage 5) of the Borgholm Formation and the Alum Shale Formation (Guzhangian–Tremadocian). Agnostoids and trilobites allowed subdivision of the succession into eight biozones, in ascending order: the uppermost Cambrian Series 3 (Guzhangian) Agnostus pisiformis Zone and the Furongian Olenus gibbosus, O. truncatus, Parabolina spinulosa, Sphaerophthalmus? flagellifer, Ctenopyge tumida, C. linnarssoni and Parabolina lobata zones. Conspicuous lithologic unconformities and the biostratigraphy show that the succession is incomplete and that there are several substantial gaps of variable magnitudes. Carbon isotope analyses (δ13Corg) through the Alum Shale Formation revealed two globally significant excursions: the Steptoean Positive Carbon Isotope Excursion (SPICE) in the lower–middle Paibian Stage, and the negative Top of Cambrian Excursion (TOCE), previously referred to as the HERB Event, in Stage 10. The δ13Corg chemostratigraphy is tied directly to the biostratigraphy and used for an improved integration of these excursions with the standard agnostoid and trilobite zonation of Scandinavia. Their relations to that of coeval successions in Baltoscandia and elsewhere are discussed. The maximum amplitudes of the SPICE and TOCE in the Gronhogen succession are comparable to those recorded in drill cores retrieved from Scania, southern Sweden. The results of this study will be useful for assessing biostratigraphic relations between shale successions and carbonate facies on a global scale. (Less)
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Sphenothallus from the Furongian (Cambrian) of Scandinavia
GFF, 2014Co-Authors: Sarah E. Stewart, John Ahlgren, Per Ahlberg, Euan N. K. Clarkson, Brigitte SchoenemannAbstract:Sphenothallus, a Palaeozoic genus of uncertain affinity, possibly a hydrozoan, is reported from the Furongian (Cambrian) of Scandinavia. This is the only known occurrence of the genus in Cambrian rocks outside of China, western North America and Bohemia, and also the first report of Sphenothallus in the Cambrian–Ordovician of Baltica. The material is from the upper Furongian (upper Protopeltura and lower Peltura superzones) of Mount Kinnekulle, Vastergotland, south-central Sweden. It consists of elongated, slightly tapering, shiny black phosphatic tubules. Scanning electron microscope photographs confirm paired internal longitudinal thickenings, typical of the genus, on opposite sides of the central lumen. The presence of the Swedish material in a low-energy, dysoxic facies is consistent with most previous occurrences.
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A Bradoriid and Brachiopod Dominated Shelly Fauna from the Furongian (Cambrian) of Västergötland, Sweden
Journal of Paleontology, 2013Co-Authors: Timothy P. Topper, Christian B. Skovsted, David A. T. Harper, Per AhlbergAbstract:A small assemblage of shelly fossils, dominated by the brachiopod Treptotreta jucunda and the bradoriid arthropod Mongolitubulus aspermachaera new species is described from a Furongian limestone of Vastergotland, south-central Sweden. Mongolitubulus aspermachaera is represented in the assemblage by individual valves and numerous, ornamented spines. Valves and spines share identical ornament and microstructure leaving no doubt that the isolated spines were once attached to the bradoriid valves. Mongolitubulus aspermachaera adds to the increasing list of spinose Cambrian bradoriid arthropods, and Mongolitubulidae new family is erected here to incorporate the genera Mongolitubulus, Tubuterium and Spinospitella. Mongolitubulus aspermachaera represents the youngest member of the new family and supplements the biodiversity of bradoriids in the Furongian, an interval when bradoriid diversity is considered to be very much on the decline. The brachiopod Treptotreta jucunda described predominantly from the ‘middle' to ‘late' Cambrian of Australia is here documented for the first time from outside Gondwana, dramatically extending the biogeographical range of the species. Other elements of the faunal assemblage include typical Baltic Furongian representatives, such as the trilobite Parabolina, the agnostoid Agnostus and the phosphatocopids Hesslandona and Vestrogothia.
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Furongian (Cambrian) agnostoids of Scandinavia and their implications for intercontinental correlation
Geological Magazine, 2012Co-Authors: Per Ahlberg, Fredrik TerfeltAbstract:Out of the 14 agnostoid species/subspecies so far recorded from the Furongian of Scandinavia, seven are excellent biostratigraphical indices and important for correlation between Baltica and other palaeocontinents. Glyptagnostus reticulatus, Aspidagnostus lunulosus and Agnostus (Homagnostus) obesus first appear at the base of the G. reticulatus Zone, allowing a precise correlation of the base of the Paibian Stage into Scandinavia. Tomagnostella orientalis and Psettdagnostus cyclopyge appear near the base of the Parabolina brevispina Zone, suggesting a correlation with the uppermost Paibian through the lowermost Jiangshanian stages. Lotagnostus americanus and Pseudagnostus rugosus have an intercontinental distribution and their first appearance in Scandinavia allows for a correlation with one of the most favourable levels for defining the base of Cambrian provisional Stage 10. In the Furongian of Scandinavia, agnostoids are conspicuously assembled in three different intervals: the lower Glyptagnostus reticulatus Zone, the lower Psettdagnostus cyclopyge Zone and the Lotagnostus americanus through lower Trilobagnostus holmi zones. The agnostoid-barren and largely unfossiliferous succession separating the lower and middle agnostoid-bearing intervals can be explained by means of subsequent dissolution of the calcareous fauna and/or a hostile environment. The middle agnostoid-bearing interval is succeeded by an anomalous succession dominated by the orthide brachiopod Orusia lenticularis, reflecting a regressive event coupled with increasing levels of oxygen at the sediment/water interface. This shallowing evidently resulted in unfavourable conditions for agnostoids.
Fredrik Terfelt - One of the best experts on this subject based on the ideXlab platform.
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Upper Cambrian (Furongian) biostratigraphy in Scandinavia revisited: definition of superzones
GFF, 2014Co-Authors: Arne Thorshøj Nielsen, Thomas Weidner, Fredrik Terfelt, Magne HøybergetAbstract:The traditional Furongian trilobite biozones of Scandinavia, recently proposed abandoned due to inconsistent boundary definitions [Terfelt, F., Eriksson, M.E., Ahlberg, P. & Babcock, L.E., 2008: Furongian Series (Cambrian) biostratigraphy of Scandinavia – a revision. Norwegian Journal of Geology88, 73–87], are resurrected and elevated to superzonal rank. These superzones are usually readily recognized in the field, even by non-specialists, and for general correlation and mapping the more wide-ranging biozones are considerably more practicable than the very detailed zonation (formerly subzonation) introduced by Terfelt et al. (2008). Formal definition of the superzones is outlined including designation of stratotype sections. The superzones are each defined by the FAD of a characterizing species group and upwards delimited by the base of the succeeding superzone. The long used Olenus, Parabolina and Leptoplastus (super)zones as well as the recently introduced Acerocarina Superzone ( = Acerocare Zone of ol...
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Furongian (Cambrian) agnostoids of Scandinavia and their implications for intercontinental correlation
Geological Magazine, 2012Co-Authors: Per Ahlberg, Fredrik TerfeltAbstract:Out of the 14 agnostoid species/subspecies so far recorded from the Furongian of Scandinavia, seven are excellent biostratigraphical indices and important for correlation between Baltica and other palaeocontinents. Glyptagnostus reticulatus, Aspidagnostus lunulosus and Agnostus (Homagnostus) obesus first appear at the base of the G. reticulatus Zone, allowing a precise correlation of the base of the Paibian Stage into Scandinavia. Tomagnostella orientalis and Psettdagnostus cyclopyge appear near the base of the Parabolina brevispina Zone, suggesting a correlation with the uppermost Paibian through the lowermost Jiangshanian stages. Lotagnostus americanus and Pseudagnostus rugosus have an intercontinental distribution and their first appearance in Scandinavia allows for a correlation with one of the most favourable levels for defining the base of Cambrian provisional Stage 10. In the Furongian of Scandinavia, agnostoids are conspicuously assembled in three different intervals: the lower Glyptagnostus reticulatus Zone, the lower Psettdagnostus cyclopyge Zone and the Lotagnostus americanus through lower Trilobagnostus holmi zones. The agnostoid-barren and largely unfossiliferous succession separating the lower and middle agnostoid-bearing intervals can be explained by means of subsequent dissolution of the calcareous fauna and/or a hostile environment. The middle agnostoid-bearing interval is succeeded by an anomalous succession dominated by the orthide brachiopod Orusia lenticularis, reflecting a regressive event coupled with increasing levels of oxygen at the sediment/water interface. This shallowing evidently resulted in unfavourable conditions for agnostoids.
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Pseudagnostus rugosus Ergaliev, 1980: a key agnostoid species for intercontinental correlation of upper Furongian (Cambrian) strata
Geological Magazine, 2010Co-Authors: Fredrik Terfelt, Per AhlbergAbstract:Pseudagnostus rugosus Ergaliev, 1980 is described from the Furongian Ctenopyge tumida Zone at Gislovshammar, Scania, southern Sweden. This is the first record of this distinctive agnostoid in Scandinavia. The species is known previously from Malyi Karatau, Kazakhstan, and northwestern Hunan and western Zhejiang, South China, and provides a newly recognized link between middle–upper Furongian successions in Baltica, Kazakhstan and South China. The occurrences of P. rugosus allow a correlation between the C. tumida Zone of Baltica, the lower Eolotagnostus scrobicularis – Jegorovaia Zone of Kazakhstan and the lower Lotagnostus americanus Zone of South China.
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Complete record of Furongian polymerid trilobites and agnostoids of Scandinavia : a biostratigraphical scheme
Lethaia, 2010Co-Authors: Fredrik Terfelt, Per Ahlberg, Mats E. ErikssonAbstract:So far, 112 polymerid trilobite species/subspecies and 13 agnostoid species/subspecies have been recorded from the Furongian (upper Cambrian) of Scandinavia. For the first time, their zonal occurrences are summarized in a biostratigraphical scheme serving as a practical synopsis for students of this interval in time. Ninety-six of the recorded polymerid trilobite species/subspecies belong to the family Olenidae whereas the remaining 16 are distributed across eight other families. Levels of increased speciation and low diversity (including stratigraphical range gaps) are conspicuous and these may be correlated with recorded physical and chemical anomalies.
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cambrian high resolution biostratigraphy and carbon isotope chemostratigraphy in scania sweden first record of the spice and dice excursions in scandinavia
Lethaia, 2009Co-Authors: Per Ahlberg, L Babcock, Mats E. Eriksson, Niklas Axheimer, Birger Schmitz, Fredrik TerfeltAbstract:A core drilling (Andrarum-3), from the classical locality at Andrarum, Scania, southernmost Sweden, penetrated a 28.90-m-thick Cambrian succession. The core comprises dark grey to black, finely laminated mudstones and shales with early concretionary carbonate lenses (stinkstones or orsten) and a few primary carbonate beds. The middle Cambrian (provisional Series 3) part of the core comprises 17.35 m, whereas the Furongian Series (upper Cambrian) part covers the remaining 11.55 m. Nineteen trilobite and two phosphatocopine genera are present in the middle Cambrian, whereas the less diverse Furongian interval yielded four trilobite and three phosphatocopine genera. Other, less frequent, faunal elements include conodonts (s. l.), brachiopods, sponge spicules, bradoriids, and coprolites. Trilobites and phosphatocopines were used to subdivide the core into seven biozones ranging from the Ptychagnostus atavus Zone to the Parabolina spinulosa Zone (P. spinulosa Subzone). Carbon isotopic analyses (δ13Corg) through the core show two important excursions, the negative DrumIan Carbon isotope Excursion (DICE) in the Pt. atavus Zone, and the Steptoean Positive Carbon Isotope Excursion (SPICE) beginning near the first appearance of Glyptagnostus reticulatus and extending upward into the Olenus and Agnostus (Homagnostus) obesus Zone. The DICE displays a peak value, in the samples at hand, of –30.45‰δ13Corg in the lower part of the P. atavus Zone. The δ13Corg values increase through the overlying L. laevigata and A. pisiformis zones and display peak values of c. –28.00‰δ13Corg in the lowermost Furongian Olenus wahlenbergi and O. attenuatus subzones. Thereafter the values decrease significantly through the O. scanicus Subzone. Both isotopic excursions have been documented from several palaeocontinents, but never before from Baltica. Moreover, for the first time these excursions are recorded from organic matter in an alum shale setting. The recorded shift of +1.50–2.00‰δ13Corg is approximately half the magnitude of the SPICE documented from other regions. This discrepancy may be related to temporal variations in the type, origin, or diagenesis of the organic fraction analysed.
Samuel A Bowring - One of the best experts on this subject based on the ideXlab platform.
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geochronology of the cambrian a precise middle cambrian u pb zircon date from the german margin of west gondwana
Geological Magazine, 2015Co-Authors: Ed Landing, Gerd Geyer, Robert Buchwaldt, Samuel A BowringAbstract:A volcanic tuff 1.0 m above the base of the Triebenreuth Formation in the Franconian Forest provides the first precise and biostratigraphically bracketed date within the traditional Middle Cambrian. The first illustration of fossils from the Triebenreuth Formation in this report and their discussion allow a more highly refined correlation within the Middle Cambrian. A weighted mean 206 Pb– 238 U date of 503.14±0.13/0.25/0.59 Ma on zircons from this subaerial pyroclastic tuff was determined by U–Pb chemical abrasion isotope dilution mass spectrometry (CA-TIMS) techniques. At c . 6.0–7.0 Ma younger than the base of the traditional Middle Cambrian in Avalonia, the new West Gondwanan date from east-central Germany suggests that estimates of 500 Ma for the base of the traditional Upper Cambrian and 497 Ma on the base of the Furongian Series may prove to be too ‘old’. Biostratigraphically well-bracketed dates through most of the Middle Cambrian/Series 3 and below the upper Upper Cambrian/upper Furongian Series do not exist. An earlier determined 494.4±3.8 Ma date from the Southwell Group of Tasmania may actually prove to be a reasonable estimate for the age of the base of the traditional Upper Cambrian. Until high precision dates are determined on the base of the traditional Upper Cambrian and base of the Furongian Series, the rates of biotic replacements and geological developments and the durations of biotic zones in the Middle/Series 3 and Upper Cambrian/Furongian Series remain as ‘best guesses’.
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Geochronology of the Cambrian: a precise Middle Cambrian U–Pb zircon date from the German margin of West Gondwana
Geological Magazine, 2014Co-Authors: Ed Landing, Gerd Geyer, Robert Buchwaldt, Samuel A BowringAbstract:A volcanic tuff 1.0 m above the base of the Triebenreuth Formation in the Franconian Forest provides the first precise and biostratigraphically bracketed date within the traditional Middle Cambrian. The first illustration of fossils from the Triebenreuth Formation in this report and their discussion allow a more highly refined correlation within the Middle Cambrian. A weighted mean 206 Pb– 238 U date of 503.14±0.13/0.25/0.59 Ma on zircons from this subaerial pyroclastic tuff was determined by U–Pb chemical abrasion isotope dilution mass spectrometry (CA-TIMS) techniques. At c . 6.0–7.0 Ma younger than the base of the traditional Middle Cambrian in Avalonia, the new West Gondwanan date from east-central Germany suggests that estimates of 500 Ma for the base of the traditional Upper Cambrian and 497 Ma on the base of the Furongian Series may prove to be too ‘old’. Biostratigraphically well-bracketed dates through most of the Middle Cambrian/Series 3 and below the upper Upper Cambrian/upper Furongian Series do not exist. An earlier determined 494.4±3.8 Ma date from the Southwell Group of Tasmania may actually prove to be a reasonable estimate for the age of the base of the traditional Upper Cambrian. Until high precision dates are determined on the base of the traditional Upper Cambrian and base of the Furongian Series, the rates of biotic replacements and geological developments and the durations of biotic zones in the Middle/Series 3 and Upper Cambrian/Furongian Series remain as ‘best guesses’.
Duck K. Choi - One of the best experts on this subject based on the ideXlab platform.
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Mansuyia Sun, and Tsinania Walcott, from the Furongian of North China and the evolution of the trilobite family Tsinaniidae
Palaeontology, 2013Co-Authors: Tae-yoon S. Park, Ju Eon Kim, Seung-bae Lee, Duck K. ChoiAbstract:The Furongian trilobite family Tsinaniidae is characterized by a highly effaced surface and forms an important constituent of the Furongian trilobite faunas of east Gondwana. However, the origin of the characteristic morphology of this family has remained unclear. Only recently has the tsinaniid trilobite Lonchopygella megaspina been suggested to represent an intermediate stage in the evolutionary transition to other tsinaniids on the basis of the trunk segmentation. Here, we report successive occurrences of four species of the kaolishaniid genus Mansuyia and a tsinaniid trilobite Tsinania canens from the Furongian (late Cambrian) Chaomidian Formation in Shandong Province, China. A cladistic analysis including these taxa reveals that the four species of Mansuyia constitute stem-group taxa to the family Tsinaniidae, rendering Mansuyia and the Kaolishaniidae paraphyletic. The youngest species of Mansuyia, M. taianfuensis, turns out to be the immediate sister taxon of the Tsinaniidae, displaying a closely similar morphology to the tsinaniid trilobite, Shergoldia laevigata. The generic and familial boundary therefore situated between M. taianfuensis and S. laevigata.
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global cambrian trilobite palaeobiogeography assessed using parsimony analysis of endemicity
Geological Society London Memoirs, 2013Co-Authors: J. Javier Álvaro, Osvaldo L Bordonaro, Gappar Kh Ergaliev, Wesley I Gapp, Duck K. Choi, L Babcock, Roger A. Cooper, Mansoureh Ghobadi PourAbstract:Abstract Palaeobiogeographical data on Cambrian trilobites obtained during the twentieth century are combined in this paper to evaluate palaeoceanographic links through c. 30 myr, once these arthropods biomineralized. Worldwide major tectonostratigraphic units are characterized at series intervals of Cambrian time and datasets of trilobite genera (629 for Cambrian Series 2, 965 for Cambrian Series 3, and 866 for the Furongian Series) are analysed using parsimony analysis of endemicity. Special attention is given to the biogeographical observations made in microcontinents and exotic terranes. The same is done for platform-basinal transects of well-known continental margins. The parsimony analysis of endemicity analysis resulted in distinct palaeogeographical area groupings among the tectonostratigraphic units. With these groupings, several palaeobiogeographical units are distinguished, which do not necessarily fit the previously proposed biogeographical realms and provinces. Their development and spatial distributions are broadly controlled by Cambrian palaeoclimates, palaeogeographical conditions (e.g. carbonate productivity and anoxic conditions) and ocean current circulation. Supplementary material: Global dataset of Cambrian Epoch 2 (A), Cambrian Epoch 3 (B) and the Furongian Epoch (C) trilobite genera are provided at: http://www.geolsoc.org.uk/SUP18669
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trilobite faunal successions across the base of the Furongian series in the taebaek group taebaeksan basin korea
Geobios, 2011Co-Authors: Tae Yoon Park, Duck K. ChoiAbstract:Abstract The base of the Furongian Series in the Sino-Korean Block has not been clearly defined due to the lack of the index taxon, Glyptagnostus reticulatus. The Sesong Formation of the Taebaek Group, Taebaeksan Basin, Korea, has been known to range from the Guzhangian Stage of the Cambrian Series 3 to the middle Furongian Series, hence embracing the base of the Furongian Series. Silicified polymerid trilobites were recovered from the middle part of the Sesong Formation. Described are a total of 18 polymerid species of 13 genera: Neodrepanura sp. 1, Teinistion sp. 1, Huzhuia sp. 1, Huzhuia sp. 2, Liostracina simesi, Liostracina sp. 1, Parachangshania monkei, Parachangshania rectangularis nov. sp., Placosema bigranulosum, Fenghuangella laevis nov. sp., Baikadamaspis jikdongensis nov. sp., Baikadamaspis sp. 1, Prochuangia mansuyi, Maladioides coreanicus, Alataspis sesongensis nov. gen., nov. sp., Chuangia sp. 1, and ceratopygids genus and species indeterminate 1 and 2. The stratigraphic occurrence of these trilobites provides a basis for recognition of five zones across the base of the Furongian Series (in ascending order): the Neodrepanura, Liostracina simesi, Fenghuangella laevis, Prochuangia mansuyi, and Chuangia zones. The Neodrepanura and Chuangia zones are provisionally adopted from the previous biostratigraphic scheme, while the three other ones are newly proposed. The recommended base of the Furongian Series in the Taebaek Group of Korea coincides with the base of the Fenghuangella laevis Zone, which appears to represent an episode of profound trilobite faunal turnover.
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ontogeny of the Furongian late cambrian remopleuridioid trilobite haniwa quadrata kobayashi 1933 from korea implications for trilobite taxonomy
Geological Magazine, 2011Co-Authors: Tae Yoon Park, Duck K. ChoiAbstract:The monophyly of the trilobite Order Asaphida has been challenged. The Superfamily Remopleuridioidea was included in the Order Asaphida, based on the ventral median suture and highly bulbous protaspis of the late Furongian–Tremadocian representatives of the group. The remopleuridioid, Haniwa quadrata Kobayashi, 1933 from the Furongian (late Cambrian) Hwajeol Formation of Korea, represents a primitive morphology of the Remopleuridioidea. This trilobite does not have a typical globular morphology of asaphoid protaspis, and the free cheeks remained yoked together during the whole of the development. This supports the previous proposition that the Superfamily Remopleuridioidea should be excluded from the Order Asaphida. In addition, the evolution of a highly globular protaspis of the Ordovician remopleuridioid trilobites from the less bulbous protaspis corroborates the possibility of multiple evolutions of a highly globular protaspis. It can be argued that the possession of a highly globular protaspis does not guarantee the membership of the Order Asaphida, and thus the concept of the Order Asaphida should be emended.
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Dikelocephalid Trilobites from the Eosaukia Fauna (Upper Furongian) of the Taebaek Group, Korea
Journal of Paleontology, 2011Co-Authors: Seung-bae Lee, Duck K. ChoiAbstract:The Eosaukia fauna is proposed for the upper Furongian trilobite assemblage from the interval spanning from the upper part of the Hwajeol Formation to the lowermost part of the Dongjeom Formation in the Taebaek Group, Taebaeksan Basin, Korea. It is characterized by the dominance of dikelocephalid trilobites comprising Eosaukia micropora, E. bella, E. acuta, Mictosaukia cf. M. globosa, and Taebaeksaukia spinata n. gen. n. sp. Taxonomic reappraisal of the genus Mictosaukia that has been employed as an upper Cambrian index taxon in eastern Gondwana reveals that more than half of the species of Mictosaukia belong in Eosaukia. This study clarifies the generic concept of Eosaukia, which provides a more reliable biostratigraphic correlation for the upper Furongian strata in eastern Gondwanan regions. The Eosaukia fauna is correlated with the “Mictosaukia” faunas from the upper Fengshanian of North China, upper Taoyuanian of South China, and upper Payntonian of Australia.
Tae-yoon S. Park - One of the best experts on this subject based on the ideXlab platform.
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Ontogeny of the two co-occurring middle Furongian (late Cambrian) shumardiid trilobites and the protaspid morphology of shumardiids
Geological Magazine, 2017Co-Authors: Tae-yoon S. ParkAbstract:AbstractShumardiid trilobites had a small, unique morphology, and formed a key constituent in trilobite faunas during the Cambrian–Ordovician. Because of their unusual morphology, they have been the subject of research s, into various aspects such as their life habit, functional morphology, evolutionary origin and ontogeny. Originally, a flat, adult-like protaspid morphology was suggested for shumardiids, but subsequently a bulbous protaspid morphology interpreted to be associated with metamorphosis was also suggested for this unique trilobite group. This article documents the ontogeny of the two co-occurring shumardiid trilobites, Akoldinioidia latus Park and Kihm and Koldinioidia choii Park and Kihm, from the middle Furongian Hwajeol Formation, Taebaeksan Basin, Korea. Interestingly, protaspides of the two shumardiids have a bulbous morphology. Given the stratigraphic occurrences of the two shumardiids, it can be inferred that commutavi protaspis appeared quite early in the shumardiid evolution. The co-occurrence of the two closely related trilobites is reminiscent of sexual dimorphism, although further evidence is required to prove it. The appearance of metamorphosis-undergoing protaspides in the Furongian shumardiids may have been due to the onset of increasing ecological pressure in the early phase of the Great Ordovician Biodiversification Event.
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Ontogeny of the Furongian (late Cambrian) trilobite Proceratopyge cf. P. Lata Whitehouse from northern Victoria Land, Antarctica, and the evolution of metamorphosis in trilobites
Palaeontology, 2016Co-Authors: Tae-yoon S. Park, Jusun Woo, Ji-hoon Kihm, Young-hwan Kim, Jong‐ik LeeAbstract:There were multiple origins of metamorphosis-undergoing protaspides in trilobite evolution: within the superfamilies Remopleuridioidea, Trinucleoidea, and within the Order Asaphida. Recent studies have revealed that the protaspides of the Cambrian representatives of the Remopleuridioidea and the Trinucleoidea did not undergo metamorphosis. However, ontogeny of the Cambrian members of the Order Asaphida has remained unknown. This study documents the ontogeny of the Furongian asaphoidean ceratopygid trilobite, Proceratopyge cf. P. lata Whitehouse, from northern Victoria Land, Antarctica. Two stages for the protaspid phase, five developmental stages for the post-protaspid cranidia, and ten stages for the post-protaspid pygidia have been identified. Interestingly, the protaspis directly developed into a meraspis without metamorphosis. A new cladistic analysis resulted in a single most parsimonious tree, according to which the presence of the bulbous commutavi protaspis turns out to be a synapomorphy for Asaphidae + Cyclopygoidea, not a synapomorphy for the Order Asaphida as previously suggested. In addition, it is inferred that there was convergent evolution of indirectly-developing commutavi protaspides during the Furongian and Early Ordovician. Metamorphosis-entailing planktonic larvae evolved in many different metazoan lineages near the Cambrian–Ordovician transition, due to the escalating ecological pressure of the Great Ordovician Biodiversification Event. Since the bulbous commutavi protaspid morphology is thought to be an adaptation for a planktonic life mode, the convergent evolution of the indirect development in the three trilobite lineages at this period might have been a result of adaptation to the early phase of the Great Ordovician Biodiversification Event.
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Mansuyia Sun, and Tsinania Walcott, from the Furongian of North China and the evolution of the trilobite family Tsinaniidae
Palaeontology, 2013Co-Authors: Tae-yoon S. Park, Ju Eon Kim, Seung-bae Lee, Duck K. ChoiAbstract:The Furongian trilobite family Tsinaniidae is characterized by a highly effaced surface and forms an important constituent of the Furongian trilobite faunas of east Gondwana. However, the origin of the characteristic morphology of this family has remained unclear. Only recently has the tsinaniid trilobite Lonchopygella megaspina been suggested to represent an intermediate stage in the evolutionary transition to other tsinaniids on the basis of the trunk segmentation. Here, we report successive occurrences of four species of the kaolishaniid genus Mansuyia and a tsinaniid trilobite Tsinania canens from the Furongian (late Cambrian) Chaomidian Formation in Shandong Province, China. A cladistic analysis including these taxa reveals that the four species of Mansuyia constitute stem-group taxa to the family Tsinaniidae, rendering Mansuyia and the Kaolishaniidae paraphyletic. The youngest species of Mansuyia, M. taianfuensis, turns out to be the immediate sister taxon of the Tsinaniidae, displaying a closely similar morphology to the tsinaniid trilobite, Shergoldia laevigata. The generic and familial boundary therefore situated between M. taianfuensis and S. laevigata.
